* simplify export and import, now that we have blender profiles for lights. The vanilla import is now more in line with the specs. If a blender profile is found, skip normal import, use the profile data instead.
* multiply energy into color rgb export (common profile).
* recalc distance taking metrics in account
lamp->energy and lamp->distance are now taken in account by calculating
the constant, linear and quadratic attenuations based on this.
The import tries to do the reverse.
Note: this will work only properly for lamps that have att1 and att2 set to
1.0 or 0.0, other lamptypes won't import correctly again.
